chore(renovate): update shell script regex for docker image detection

- modify regex pattern in custom manager to optionally match lines starting with '# renovate' comment
- improve pattern to handle newlines before variable assignment for better compatibility

renovate.json

@@ -316,7 +316,7 @@
       "managerFilePatterns": ["/(^|/).+\\.sh$/"],
       "matchStrings": [
         // 调试正则表达式: https://regexr.com/8jlns
-        "([\\S]+=)(?<depName>[\\S]+):(?<currentValue>[\\S]+)"
+        "(?:# renovate)(?:\\n+)?([\\S]+=)(?<depName>[\\S]+):(?<currentValue>[\\S]+)"
       ],
       "datasourceTemplate": "{{#if datasource}}{{{datasource}}}{{else}}docker{{/if}}"
     }